1. Field of the Invention
The present invention relates, in general, to an air conditioning device for a car, a foot-door of which is of a double structure.
2. Description of the Related Art
FIG. 1 is a cross-sectional view illustrating an air conditioning device of the prior art, FIG. 2 is a perspective view illustrating a door of the air conditioning device of FIG. 1, FIG. 3 is a cross-sectional view illustrating the air conditioning device of FIG. 1 in which the door is open in foot and vent directions, and FIG. 4 a cross-sectional view illustrating the air conditioning device of FIG. 1 in which the door is open in foot and defrost directions.
In FIG. 1, the air conditioning device includes a case 10 in which air conditioning is carried out, an air inlet 20 provided in the case 10, and an evaporator 30 provided below the air inlet 20.
The air inlet 20 serves to direct air introduced therethrough to the evaporator 30, which in turn serves to cool the temperature of air introduced therein.
In addition, a temperature-control door 40 is provided in front of the evaporator 30, a heater core 50 is provided in front of the temperature-control door 40, and a foot-door 60, a vent-door 70, and a defrost door 80 are provided above the heater core 50.
In accordance with an installing position or a structural feature of an air conditioning device in a car, the foot-door 60 is placed on a side face of the case 10 relatively vertical to the ground when in a closed state, and the vent-door 70 and the defrost-door 80 are on the case 10 relatively horizontal to the ground when in a closed state.
The temperature-control door 40 is placed between the evaporator 30 and the heater core 50 such that, when in a cooling mode, it rotates downwards to cut off an inflow of air into the heater core 50, and, when in a heating mode, it rotates upwards to cut off an air path so as to allow air to flow in the heater core 50, and further, when in a mixing mode, it is placed between the former positions to induce cool air and warm air to be mixed.
Thus, depending upon the position of the temperature-control door 40, an air conditioning mode is selected from the cooling mode, the heating mode, and the mixing mode.
That is, when the temperature-control door 40 rotates to the positions depicted in solid line, dashed dotted line, and dotted line, it is in the heating mode, the cooling mode, and the mixing mode, respectively.
Here, in the mixing mode, a portion of cool air, which is heat-exchanged while passing through the evaporator 30, passes through the heater core 50, and remaining portion passes through the air path without passing through the heater core 50, so that warm air heat-exchanged while passing through the heater core 50, and cool air not passing through the heater core 50, are mixed together in a mixing space MS provided above the evaporator 30 and the heater core 50, and the mixed air is discharged out into a room.
The foot-door 60 is configured such that opposite blades 64 and 65 are provided about a center axis 62 as shown in FIG. 2. The configurations of the vent-door 70 and the defrost door 80 are identical to that of the foot-door.
The operation of the conventional air conditioning device will now be described as follows.
If it is required to control the temperature or the quantity of air in a car, a driver touches a control button to operate an air conditioning device.
Here, air flows out in a foot direction 92, a vent direction 94, or a defrost direction 96. The driver can selectively set a direction of air to any one of foot direction 92, vent direction 94, and defrost direction 96, or otherwise either to both foot direction 92 and vent direction 94 or to both foot direction 92 and defrost direction 96 at the same time.
In these cases, when it is set that air flows in both foot direction 92 and vent direction 94 at the same time, such that high temperature air flows towards the foot direction 92 and low temperature air flows towards the vent direction 94, the air conditioning device operates as shown in FIG. 3.
That is, as shown in FIG. 3, the temperature-control door 40 is positioned in the mixing mode so that a portion of air flowing from the evaporator 30 flows upwards along a right sidewall in a first direction 84, and the remaining portion passes through the heater core 50 and flows upwards along a left sidewall in a second direction 86.
Herein, since an inlet of a path in the foot direction 92 is formed perpendicular to the first and second directions 84 and 86, air flowing in those directions does not easily flow in the path of the foot direction 92.
If the foot-door 60 opens at a certain angle from a closed position as shown in FIG. 1, a lower blade 65 of the foot-door 60 rotates counterclockwise at an angle between 45° and 90° towards the inside of the case 10, so that cool air rising along the first direction 84 and warm air rising along the second direction 86 are properly mixed together by the lower blade 65 of the foot-door 60 and flow in the foot direction 92.
However, since the opposite blades 64 and 65 of the foot-door 60 are of a single-plate structure, depending upon a rotation angle of the opposite blades 64 and 65, air flowing in the path in the foot direction 92 becomes greatly varied in its temperature and amount.
Thus, there is a problem in controlling the temperature and amount of air to flow.
Such a problem also occurs even when a driver operates the foot-door 60 and the defrost-door 80 at the same time.